1. Field of the Invention
The present invention generally relates to a head base unit, and more particularly to an optical head base unit forming a part of an optical apparatus.
2. Description of the Related Art
An optical disk apparatus has a structure including an optical head base unit. The optical head base unit has an optical head that is movably supported by a guiding rod on a base portion. The height of the guiding rod is adjustable so that the optical head can move parallel to the plane of an optical disk (e.g. CD-ROM) which disk is supported and rotated on a turntable.
FIGS. 7A, 7B, and 7C show a height adjustment mechanism of a guiding rod 20 of a conventional optical head base unit. The height adjustment mechanism is structured having a coil compression spring member 10 and an adjustment screw member 11. The coil compression spring member 10 disposed on a base plate 21 exerts a force on the guiding rod 20 upward in the direction Z1 so that the guiding rod 20 is pressed against the bottom surface of a flange 11a of the adjustment screw member 11. The adjustment screw member 11 is screwed into the base plate 21. In a case where the adjustment screw member 11 is rotated in a tightening direction with a screwdriver, the guiding rod 20 is pressed downward so that the height of the guiding rod can be adjusted to be lower. In a case where the adjustment screw member 11 is rotated in a loosening direction, the height of the guiding rod 20 can be adjusted to be higher.
Owing to the conventional height adjustment mechanism being structured by the coil compression spring member 10 and the adjustment screw member 11, the conventional height adjustment mechanism has a problem of requiring excess components and steps during assembly.
Furthermore, since the spring force of the coil compression spring member 10 is directed not only upward against the guiding rod 20, but also downward (direction Z2) against the base plate 21, creep or deformation may occur in some cases.